Manual dexterity is fundamental for maintaining independence in many basic and instrumental activities of daily living. Two important components of skill learning are the learning process itself (motor acquisition), and the ability to transfer what has been learned to new conditions and task variants (motor generalization). Many studies have documented declines in the ability of the elderly to learn new manual motor skills. Even though older adults exhibit reduced rates and magnitudes of skill acquisition in comparison to young adults, our recent work demonstrates that they show normal motor generalization. We propose that this newly documented age-related dissociation between acquisition and generalization is fundamentally important to clarifying the mechanisms and course of age-related motor declines. Moreover, this dissociation may provide new insights into acquisition and generalization processes and their neural underpinnings in the young adult. Recent behavioral and brain imaging investigations of skill acquisition suggest that motor learning consists not only of sensorimotor processes but also spatial cognitive processes, particularly during the early stages of learning. In the first aim of this project, we will use both behavioral and brain imaging techniques to investigate whether age-related declines in skill acquisition are associated with deficits in the early, spatial processing stages of learning. We will test this hypothesis using tasks that represent the two major classes of skill learning: sensorimotor adaptation and sequencing behaviors. The second aim will examine whether motor generalization is associated with reduced involvement of these early learning spatial processes for both young and older adults. Thus, the overarching goal of this project is to describe and quantify the neural and behavioral mechanisms of age-related changes in skill acquisition and motor generalization. We predict that age-related declines in both sequence learning and sensorimotor adaptation are a result of deficits in the early, spatial cognitive aspects of skill acquisition. We predict that motor generalization, in comparison to original task learning, results in a reduced reliance on the spatial cognitive processes that are engaged during early skill acquisition, thus allowing for normal motor generalization in older adults.